African Union and Somali forces have launched a military operation against what they say is a major training camp for al-Shabab militants outside Somalia's capital.

The African Union Mission for Somalia (AMISOM) said in a statement Wednesday the operation aims to capture Lanta-Buro village, 40 kilometers west of Mogadishu.

Officials hope capturing the village will help secure the capital, which is preparing to host a constituent assembly that aims to end 12 years of transitional rule in Somalia.

The al-Qaida-linked al-Shabab once controlled much of Somalia and nearly all of Mogadishu. But it has lost most of its territory during an 19-month offensive involving African Union forces, the Somali government, Ethiopia and Kenya.